Method of making spring lock nuts



w. A. BERGSTROM Re. 20,916 METHOD OF MAKING SPRING LOCK NUTS 7 Nov. 15,1938.

I Original Filed May 27, 1935 IN ENTO. We; I

A TTORNEYZ Reissued Nov. 15, 1938 PATENT OFFICE 20,916 METHOD OF MAKINGSPRING LOCK NUTS William A. Bergstrom,

Renchtite Chicago, Ill., assignor to Spring Nut Company,

San Fran cisco, CaliL, a corporation of California Original No.2,035,859, rial No. 23,629, May

. 6 Claims. This invention relates to spring lock nuts, and

to the method of making them.

An object of my invention is the provision of nuts which, when applied,are self-locking by their spring action and which may be used aplurality of times without permanent set or deformation taking placetherein while they are in functioning position, that is, while undernormal strain.

Another object of my invention is to provide a method of making suchspring lock nuts.

Other objects of theinvention will be on reading the appendedspecification.

Referring to the drawing which forms a part of this specification- Fig.l is an elevation of the nut itself; and

Fig. 2 is a sectional view showing the nut in applied position.

The nut ll] follows the usual standards as to its various dimensions forpractical purposes, and it may be of any desired shape, that is, squareor hexagonal.

It differs from standard nuts as to its base ii and in being providedwith a slot l2. The bore of the nut is indicated at l3, and the base ofthe nut from the point l4 to the edge 95 lies in a plane at right-anglestothe axis of the bore. The base of the nut, however, slopes downwardlyfrom the point I to the outer edge l6 which is rounded, so

apparent that when the nut is screwed down, the part it will contactappear.

On the same side of the nut as the part I5, I provide the stepped slot[2, which enters the nut from the lower part thereof and is' directedobliquely upwardly to a point ll which is past the axis of the nut. Theslot may be comparatively first for a purpose which will now narrow atits inner part, and is provided with a.

- is below the slot to bend upwardly with respect to a slot.

shoulder I8 whereby the slot is wider at the outer part of the nut thanat the inner.

' On Fig. 2 I illustrate the nut 18 applied to the threaded end [9 of abolt .20 against a work surface or other suitably supported element M.the nut is turned down, the part l contacts first with the element 2|,and as it is turned further, it becomes necessary for the part of thenut which the rest of the nut and this is permitted by the As a result,the threads below the slot are given a clamping action when the nut isforced tightly into position.

I make my nuts of a material which is well adapted to the functions andpurposes above indicated. This material should be strong and tough.having sufficient resiliency to cause the bending or locking actionrequired. yet not be dated March 31, 1936, Se- 27, 1935.lBiSSllB.OCt0bBl: 14, 1937, Serial Application for No. 169,075

subject to permanent deformation by being used. It should be of such acharacter as to be' easily milled or cut in order that theslottingoperation may be eifected at minimum cost, and it should also respondproperly to the process of hardening. The material should be such thatthe threads may be thrown out of alignment by the normal use of thenutfand then returned to exact alignment when the nut is removed fromthe work so that the nut may be used again. The nut may be indicatedcharacter, and I have found that steels having a carbon content of about0.4% to 0.6% are well adapted for this purpose and while the carboncontent may be varied above and below these limits without departingfrom the spirit and scope of this invention, the'best results, wheresteel is the metal used, may be said to be obtained when the carboncontent is between these limits, preferably between 0.5% and 0.6%.

In the manufacture of the nuts I ordinarily start with flat bars fromwhich the nut-blanks may be made, preferably by hot-forging althoughother methods, such as cold punching and rolling, are well adapted tothe purpose. In making these blanks the base of the nut is given thepeculiar shape above described. The slots may be produced by cutting,breaching, milling, or any other suitable method, and this slotting maybe performed cold.

After slotting, the blank is tapped, that is, threads are cutinteriorlyin the bore, and it is important that the slotting operation precede thetapping operation in order to avoid damage to the threads, which mayoccur if the nut be slotted after the threads are present.

Thereafter the nuts are hardened by heating. drawing and quenching inorder to develop the required resiliency or springiness therein;' and,this must be so great that the slot will reopen to its normal positionon removal of the nut fronr the work, or at least as nearly so as isrequired to re-align the threads to their normal alignment, even afterthe slot has been entirely closed by pressure.

When the steel, above described is used, the hardening is bestto a pointwithin the range of 255 to 302 on the Brinell scale of hardness,although variation above or below this range may be used in carrying outthis invention to produce nuts having the characteristics herein abovedescribed.

I have referred to various details by way of illustratlon, but it is tobe understood that various changes may be made without departing fromthe forging the bar to the desired shape of the nut and forming the nutblank, then slotting the, nut blank and subsequently thereto tapping thenut blank,

- and finally hardening the nut by a heating, drawing andquenchingoperation to adegree equivalent to a Brinell hardness testwhich lies within a range comprising the range of 255.to 302;

2. The method of making a spring nut which consists in first utilizingfor this purpose a bar of steel of a strong, tough, free milling naturecontaining about 0.5% to 0.6% carbon, then hotforging the bar to thedesired shape of the nutand formingthe. nut blank, then slotting the nutblank and subsequently thereto tapping the nut blank, and finallyhardening the nut by a heating, drawing and quenching operation to adegree equivalent to a Brineil hardness test of about 255 to 302.

3. The 'method of making a spring nut consisting in using a bar ofstrong, tough, free milling steel having sufiicient carbon-content toprovide the aforesaid characteristics, hot forging the bar to the shapeof the nut and forming the nut blank,- slotting the nut blank andsubsequently tapping the blank, and hardening said nut by heating.quenching and drawing it before final completion to develop theresiliency required to cause the nut and parts thereof to assume initialshape or position after being fiexed. I

4. The method of making-a slotted spring nut having that portion of itsinner face corresponding to the slot angularly disposed to the remainderof said face, consisting in forginga bar of strong,

tough, free milling metal to the external shape of the nut includingsaid angularly disposed face 4 20,916 spirit of'the invention the scopeof which is deportion to form the nut blank, slotting the nut inalignment with the angularly disposed face portion, tapping the blank,and finally hardening the nut by heating, quenching and drawing it todevelop the resiliency required to cause that portion of the nut betweenthe slot and said angularly disposed face portion to return toitsinitial position after being held flexed.

'5. The method of making a slotted spring lock nut wherein the slot liesat an acute angle to the normal outer and inner faces of the nutand thatportion of the inner face of the nut aligned longitudinally of its axiswith the slot is angularly disposed to the remainder of such faceconsisting'in employing a bar of strong, tough, free-milling metal,forging a nut blank therefrom having the required external shapeincluding said angularly disposed face portion, creating a bore in theblank so formed; angularly slotting the blank in align- .mentlongitudinally of the axis of the nut with the angularly disposed faceportion of the blank, tapping the bore of the blank, and hardening thenut by heating, quenching, and drawing to develop the resiliencyrequired to return that part of the nut defined by the slot and theangularly disposed face portion to its normal position after distortionor fiexing.

6. The method of making a spring lock nut consisting in forming a blankto the desired external shape with a portion of its inner face angularlydisposed to the remainder thereof, forming a bore in the blank, slottingthe blank at an angle to the faces thereof in alignment longitudinallyof its axis with saidangularly disposed portion of the inner face,threading the bore of the blank, and hardening the nut thus formed byheating, quenching and drawing, whereby it will have the resiliency toreturn that portion thereof defined by the slot and the angularlydisposed portion of the inner face to its normal position afterdistortion or flexing.

wmiAM A. BERGSTRDM.

